With the development of computer and network related technologies, many users choose to purchase or sell products (e.g., goods or services) over a network. For example, by the use of a client-sever system, users may conduct a search over the network. Typically, during the e-commerce process, only the server knows who is searching for what. However, sellers may not know the potential buyers who are searching for their products, and buyers with same interests may not have an easy way to exchange ideas on their searches. On the other hand, the search activities are typically individual based, and thus do not have the liveness and excitement of real world shopping. For example, buyers of the same interests may not put their heads together on a hot shopping area.